Our Conservation Officer helps to monitor a very rare butterfly ahead of Christmas

Our Conservation Officer, Jack, certainly has been busy in the build up to the Christmas holidays. He recently joined the Wildlife Trust of South and West Wales, Butterfly Conservation and other volunteer wildlife recorders at one of the Wildlife Trust reserves. The aim? To assess the population of a pretty rare butterfly known as the ‘brown hairstreak’.

The rare brown hairstreak butterfly

During winter, not many butterflies can be seen on the wing as it’s far too cold for them! However, the team can assess this butterfly by finding and counting their tiny white eggs. This method means that adult butterflies aren’t disturbed, as this may well have an effect on breeding.

These butterflies are very picky as they only lay their eggs on young blackthorn trees, so their numbers have dropped due to excessive hedge cutting over the years. Once hatched, in springtime, the caterpillar crawls upwards to munch on the freshly emerged, juicy blackthorn leaves. Adults emerge from late July to October and spend time high up in the canopies of ash trees, feeding on honeydew produced by aphids.

The tiny white eggs of the brown hairstreak can be hard to spot!

The tiny white eggs are about the size of a pinhead – certainly not the easiest thing to find and count! Young blackthorn branches are scanned up and down to check for small white dots, once an egg is found it is marked with a piece of natural cotton thread making it easier to check and determine the total.

Natural cotton threat is used to mark the areas where eggs are found in the blackthorn branches

The brown hairstreak butterfly

If you’d like to get involved with butterfly conservation in your area, you can contribute through Butterfly Conservation or by assisting your local Wildlife Trust